1. Field of the Invention
This invention relates generally to an industrial robot apparatus and, more particularly, to an industrial robot apparatus having a horizontal articulation type arm and used to palletize or depalletize corrugated cardboard boxes or the like onto or from a pallet.
2. Description of the Related Art
Referring to FIG. 4 which is a plane view of a conventional industrial robot apparatus of this kind, a robot body 1 has a vertical housing 2 and a slider 9 movable in the vertical direction along the housing 2. The slider 9 is moved by a servo motor 3 disposed on an upper end portion of the housing 2. A first articulation 16 capable of rotating by only an angle .theta..sub.1 is attached to the projecting end of the slider 9. One end of a first arm 19 is connected to the articulation 16. A second articulation 17 capable of rotating by only an angle .theta..sub.2 is connected to the other end of the first arm 19, and one end of a second arm 20 is connected to this articulation. A wrist 18 capable of rotating by only an angle .alpha. is connected to the other end of the second arm 20.
Conventionally, this horizontal articulation type of robot arm is used for palletizing or depalletizing corrugated cardboard boxes or the like.
However, as shown in FIG. 5, in a case where pallets 21a and 21b are disposed close to each other and where corrugated cardboard boxes 22 are palletized onto one 21b of the pallets, there is a risk of interference between the first arm 19 and corrugated cardboard boxes 22 on the other pallet 21a depending upon the manner of stacking the corrugated cardboard boxes 22. There is also a similar risk where the corrugated boxes 22 are depalletized.
The palletizing or depalletizing may therefore be difficult, and furthermore it is necessary to fix the robot arm operation in accordance with a right hand system or a left hand system.